The Thorp T-18 Tiger is a two-place, all-metal, plans-built, homebuilt aircraft designed in 1963 by John Thorp. The aircraft was originally designed as an open cockpit aircraft, powered by a 65hp military surplus Lycoming engine. It evolved into a fully bubble canopied aircraft powered by engines of up to 200 hp.

Photos of the Thorp T-18 "Tiger"
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The T-18 was designed to be easily constructed from sheets of aluminum. It was originally designed with an open cockpit and with the cylinder heads protruding through the engine cowling in the interests of simplicity. Even as originally designed, the cruising speed was quite high. The design showed great potential for higher performance and so modifications were created to install larger, cowled Lycoming engines and a bubble canopy. These modifications allow a T-18 with 125 hp to cruise at 160 mph and higher powered examples to cruise in excess of 200 mph (322 km/h). Some aircraft have been constructed with retractable landing gear. These performance improvements made the T-18 one of the most popular homebuilt designs of the 1970s and early 1980s.